During the development of aircraft, commencing with the late 1950's and up to present day, speeds have increased to the extent that it is no longer out of the oridinary for aircraft to fly faster than the speed of sound (Mach I or greater). Such speeds have lead to at least two problems to which considerable attention is being given toward working out the solutions therefor.
One of these problems concerns drag, and more specifically parasite drag which is a function of airplane configuration, altitude, and speed. As the speed of an aircraft approaches Mach I, while induced drag is decreased to almost nil, parasite drag increases remarkably. More specifically, the ratio of parasite drag at two speeds varies as the square of the ratio of the relative speeds. Thus, at supersonic speeds, parasite drag has increased to a point that it has a considerable effect on speed, fuel consumption, and the like. Further, parasite drag varies directly with the equivalent parasite area (portions of surface which cause drag). Therefore a reduction of 50-70 percent in equivalent parasite area will have a similar effect on parasite drag.
The second consideration or concern at extremely high speeds is the sonic boom phenomenon which occurs at speeds near the speed of sound or Mach I. Sonic boom is generated by the formation of a vacuum or partial vacuum behind the trailing edge of any type of airfoil traveling at or near the speed of sound. The shock waves which are separated by the airfoil at such speeds do not come together fast enough to close immediately behind the trailing edge, thus a vacuum or partial vacuum is left. When the shock waves from above and below subsequently slam together a loud slap or boom is generated.
Considerable efforts have been made to solve the problems of sonic boom, as well as to eliminate parasite drag. To the knowledge of the inventor, however, none of such efforts have been concentrated to a single solution affecting both problems. Most of the drag solutions have been directed toward the shaping of various aircraft sections to eliminate the drag. One attempt to eliminate sonic boom is illustrated in the U.S. Pat. No. 3,776,489 to Wen et al. In the Wen et al. patent one or more air inlets are provided in the wing, elevators, and rudder into which a small amount of air is permitted to enter. The incoming air is routed through a path that is both parallel and transverse to the flight path as it travels from front to rear to simultaneously cool the leading edge of the wings, elevators, and rudder, and to partially fill or spoil the vacuum behind the trailing edges of such airfoils. While the concept of spoiling the vacuum is taught in the Wen et al. patent, that approach leads to further problems especially as far as drag is concerned. No reduction of drag is achieved because any air which may enter the front openings becomes resulting drag because of the curved path which it takes. At such speeds, a backlash is likely to occur from trying to divert the air streams which enter the wings, with the result that structural failure could occur. It is important to note that the Wen et al. patent is not at all concerned with drag. However, any attempt to considerably increase the amount of air taken in through the front openings would definitely involve drag problems.